The present invention relates to novel uses of corrosion inhibitors in fuels and lubricants.
Corrosion inhibitors are standard additives in fuels and lubricants, which are often based on structures containing acid groups, for example dimer fatty acids.
A disadvantage of these corrosion inhibitors is that they have a tendency to precipitate, especially in the presence of calcium ions, as a result of which their corrosion-inhibiting action is reduced. The deposits formed as a result of this precipitation can additionally impair the working of engines, engine constituents or parts of the fuel system, especially the injection system, specifically the injection pumps or nozzles.
The “injection system” is understood to mean the part of the fuel system in motor vehicles from the fuel pump up to and including the injector outlet. “Fuel system” is understood to mean the components of motor vehicles that are in contact with the particular fuel, preferably the region from the tank up to and including the injector outlet.
In one embodiment of the present invention, the inventive compounds counteract deposits not just in the injection system but also in the rest of the fuel system, here especially deposits in fuel filters and pumps.
The problem addressed was therefore that of providing corrosion inhibitors which exhibit elevated compatibility with respect to calcium ions and at the same time maintain their effect as a corrosion inhibitor.
The problem is solved by the use according to the claims.
U.S. Pat. No. 3,382,056 teaches the use of low molecular weight copolymers comprising olefins and succinic acid and derivatives thereof in copolymerized form as anti-rust additives in refined fuel compositions.
JP 55-085679 teaches the use of hydrolytically opened copolymers of molar mass Mw from 2000 to 30 000 from α-olefins having 20 to 60 carbon atoms and maleic anhydride as oil-soluble rust inhibitors in mineral oil or lubricants.
U.S. Pat. No. 5,080,686 and EP 299120 disclose that alkyl- and alkenylsuccinic acids and derivatives thereof and copolymers comprising olefins and succinic acid and derivatives thereof in copolymerized form function as corrosion inhibitors in oxygenated fuel systems.
It is not apparent from any of these documents that the corrosion inhibitors of the invention have elevated compatibility with respect to calcium ions.